'Free' will.
I've been listening to Adam Conover's podcast lately, and he's had some discussion with guests on free will, and whether it exists.
It seems to me that usually the argument is actually about the definition of 'free' in 'free will' as different discussions seem to assume something different, but don't really address that.
Adam had Robert Sapolsky on first, and they mentioned Daniel Dennett who is a philosopher. Dennett believes in free will, but his definition of free seems to mean 'free of the lack of agency'. So free will for him is pretty much just a sense of responsibility. If you don't have a serious brain injury or you aren't in solitary confinement then you have free will because you can choose to do the right thing.
OK, that's not really what people are talking about when discussing whether free will is an illusion though.
Adam more recently had Kevin Mitchell on, a neuroscientist who agrees with a materialist deterministic universe, but believes that free will is essentially the emergent behaviours arising in complex systems like people, and although physical processes govern the machinery of life the enormous complexity of that life-machine gives us free will.
Mitchell's definition of free seems to be 'free of the lack of basic impulse control'. I think by his definition a bee hive or ant colony has free will, or I guess an economy has free will as they exhibit choices and changes enacted without individual parts actually forcing anything.
Robert Sapolsky is another neuroscientist who completely disbelieves in free will, arguing that in a materialist, deterministic universe -- which our brains and bodies are made of and exist in -- there's no room for choice and every action we take is the culmination of our lives thus far, and our parent's lives and our entire genetic history, and cultural history, and so on. His definition of free is 'free of determinism'.
And I think Sapolsky's definition of 'free' is the one which most people, who haven't thought about it too hard, or simply cannot grasp the idea that our subjective experience may be flawed, would adopt when thinking about free will.
And I also wholeheartedly agree with Sapolsky. Free will is a very, very convincing illusion, our brains are deterministic machines, life is an ongoing complex chemical reaction fed by the sun (and according to the 2nd law of thermodynamics will end when the sun runs out of energy,) exhibiting extraordinary emergent behaviours, including self awareness in many animals, which isn't particularly surprising.
But it seems the illusion is so convincing and people don't seem to grasp that subjectivity is not at all reliable for scientific observations, and so the argument continues.